1. Field of the Invention
The present invention is related to systems and methods to bring amplifier systems to steady state.
2. Background Art
Low power electronic circuits usually have a complex set of power-down modes to save as much power as possible. However, these circuits often also have a specific response time requirement to power-up requests. Therefore, the circuits need to be able to wake-up relatively quickly. The power-up time for the circuits is determined by the capacitance on each node of the circuit and the amount of current available to charge that capacitance to the desired steady-state voltage. In amplifiers or operational transconductance amplifiers (OTAs) with differential inputs and differential outputs, the circuits need to settle to an operating point both differentially and common-mode. Often, such differential input/output amplifiers have a common-mode control circuit that sets the common-mode voltage levels in the circuit to desired levels.
Often, powering up of these circuits within the specified time takes more power (current) than is needed for steady state operation, resulting in conflicting design requirements. This is because if a designer limits a current for a low power circuit, the designer is also limiting the minimum power-up time. For example, circuits are designed to handle the power-up requirements, which results in wasted power during steady-state operation. Also, a first stage of a two-stage Miller-compensated amplifier must have very low current for stability of the circuit, which can lead to deteriorating of the power-up time.
Therefore, what is needed is a system and method that would allow an amplifier to remain stable and achieve power-up within a required time period, but that does not require more power than a steady-state operation of the amplifier.